Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?
From: Lauri Pietarinen <lauri.pietarinen_at_atbusiness.com>
Date: 10 Mar 2003 11:24:40 -0800
Message-ID: <e9d83568.0303101124.1923e2d3_at_posting.google.com>
Date: 10 Mar 2003 11:24:40 -0800
Message-ID: <e9d83568.0303101124.1923e2d3_at_posting.google.com>
jan.hidders_at_REMOVE.THIS.ua.ac.be (Jan Hidders) wrote in message > Well, your specific example involves recognizing that duplicate elimination
> is not necessary in the view. That was something that was researched as
> (relatively) recently as 1994:
>
> http://www.informatik.uni-trier.de/~ley/db/conf/icde/PaulleyL94.html
The subject has been covered even earlier in a paper by Hugh Darwen published in Relational Database Writings 1989-1991. The name of the paper is "The Role of Functional Dependence in Query Decomposition". It provides an algorithm for deriving all candidate keys from a relational expression (or view).
regards,
Lauri Pietarinen
Received on Mon Mar 10 2003 - 20:24:40 CET